Date of Original Version
Abstract or Description
The use of motion strategies to eliminate uncertainty, without the use of sensors, is considered. The approach is demonstrated within the context of a simple method to orient planar objects. A randomly oriented object is dropped into a tray. When the tray is tilted, the object can slide into walls, along walls, and into corners, sometimes with the effect of reducing the number of possible orientations. For some objects a sequence of tilting operations exists that leaves the object's orientation completely determined. An automatic planner is described that constructs such a tilting program, using a simple model of the mechanics of sliding. The planner has been implemented, the resulting programs have been executed using a tray attached to an industrial manipulator, and sometimes the programs work. The authors explore the issue of sensorless manipulation, tray tilting in particular, within the context of a formal framework described by T. Lozano-Perez, M.T. Mason, and Russ Taylor (1984). It is observed that sensorless motion strategies perform conditional actions using mechanical decisions in place of environmental inquiries.
IEEE Journal of Robotics and Automation, 4, 4, 369-379.